Subtle changes in the brain and blood may occur years before memory loss and other symptoms of Alzheimer’s disease become apparent, according to a new report. The findings offer new clues about how Alzheimer’s progresses and could help doctors to identify the disease at earlier stages, when treatments may be most effective. Understanding that Alzheimer’s is a decades-long process could also encourage people to take steps now to help fend off or delay the onset of symptoms years down the road.
The study, from researchers at the Mayo Clinic, used data from 2,082 men and women in the Mayo Clinic Study of Aging, a long-running study of brain health in volunteers living in Olmsted County, Minnesota. Participants underwent regular blood tests and brain scans to look for signs of Alzheimer’s, including the presence of the toxic proteins beta-amyloid and tau, both hallmarks of the disease. As levels of beta-amyloid accumulate in the brain, they clump together to form hard plaques, while tau forms spaghetti-like tangles between brain cells. Participants also completed regular tests of memory and thinking skills.
The researchers found that in those at high risk for Alzheimer’s disease, many Alzheimer’s-related changes began to accelerate at specific ages. Measurable declines in cognitive performance tended to speed up in people during their late 50’s, followed in their early 60’s by more rapid brain accumulation of beta-amyloid.
By the late 60’s to early 70’s, biomarkers of tau damage and neurodegeneration showed more pronounced increases. Several blood-based markers of Alzheimer’s disease showed steeper changes around ages 68 to 72, alongside more evident brain wasting, particularly in brain regions critical for memory.
“This population-based study provides an integrated view of age-related patterns across multiple Alzheimer’s biomarkers measured in blood and imaging, plus cognition,” said study author Mingzhao Hu, assistant professor in Mayo Clinic’s Department of Quantitative Health Sciences. “By estimating the ages when changes in health markers become more noticeable, the results show that many of these shifts tend to happen from late 50’s through early 70’s.”
The observed changes reflect general patterns seen in a large patient group; individual results can vary widely from person to person. But better understanding the timeline of Alzheimer’s disease progression could be critical for shifting care from late-stage treatment to earlier detection and prevention, the researchers say.
“As Alzheimer’s research shifts toward prevention and earlier treatment, blood biomarkers will play a central role in identifying who is best suited for these therapies,” said Dr. Jonathan Graff-Radford, the study’s senior author and chair of Behavioral Neurology at the Mayo Clinic. “Knowing when these biomarkers start to change, and when they relate to cognitive impairment, helps point us to the ages when prevention screening could have the greatest impact.”
The results of the study, published in the journal Alzheimer’s & Dementia, also reinforce the growing role of blood tests in Alzheimer’s research and care, which are easier to perform and far less expensive than brain scans. Blood test results showed patterns similar to those detected by brain imaging, suggesting they could be used to monitor disease-related changes over time and identify people at higher risk.
In the meantime, the findings underscore the importance of preventive measures to help stem the onset of Alzheimer’s disease. While genetics, advancing age and other factors account for most cases of Alzheimer’s, research suggests that 40 percent of dementia cases could be prevented or delayed by targeting 12 modifiable risk factors throughout life. Among the recommendations:
- Try to keep systolic blood pressure (the top number) to 130 or less from age 40 and beyond.
- Aim for a heart-healthy diet rich in whole and unprocessed foods and rich in plant foods. Include fish a couple times a week.
- If you drink alcoholic beverages, keep it moderate — no more than one to two drinks a day.
- If you smoke, quit. Quitting smoking at any age has benefits that begin immediately.
- Try to maintain a healthy weight, which can lower the risk of diabetes and other chronic ailments tied to dementia.
- If you are having hearing trouble, make sure to get a hearing aid, and protect the ears from loud noises that can cause permanent damage.
- Avoid exposure to air pollution, including secondhand smoke.
- Get regular physical activity throughout life. Starting exercising at any age has benefits that begin immediately.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, PhD, of The Fisher Center lab at The Rockefeller University.
Source: Mingzhao Hu, David S. Knopman, Terry Therneau, et al: “Breakpoints in Alzheimer’s disease biomarkers and cognition across the aging spectrum: The Mayo Clinic Study of Aging.” Alzheimer’s & Dementia, the Journal of the Alzheimer’s Association
